ON QUINONE. WALLACE. 309 



The method of separation was by no means complete, but 

 nearly 2 grams of diphenyl were obtained. 



DISCUSSION. 



The organo-magnesium halide quinone compounds, which 

 form with such energy on the addition of quinone to the 

 organo-magnesium halide , are not stable , but decompose when 

 exposed to the air. The bromide is blue and the iodide is 

 green. Their formation is possibly in accordance with the 

 following equation : 



I. CH\ /CH 



\C-O-O-CC + 2 R Mg. X = 



CH/ \CH 



CHx/ COMgX x/ R \/ CH: 

 CH/ R /\ COMgX/ X CH 



Two molecules of the organo-magnesium halide are used to 

 each molecule of quinone. 



The formation of the quinhydrone may be explained by 

 the production first of hydroquinone, as shown in the following 

 equation : 



II CH v COMgX R / CH HOH 



N/ \/ S/ _i_ 



R /^ COMgR 7 \ CH HOH 

 OH OH 



CH - ^ CH 



The hydroquinone then reacts with the unattacked quinone, 

 the reaction being expressed by the following equation : 

 III. C 6 H 4 (OH) 2 + C 6 H 4 2 = [C 6 H 4 (OH) 2 + C 6 H 4 O 2 ] 



The production of diphenyl in the action of phenylmag- 

 nesium bromide quinone is evidence in support of the reaction 

 as given in equation II. 



